Tahoe Code SVN development

Finished implementation of traction boundary conditions and body forces
on the coarse scale equations. NOTE: that all VMS input files now need
to be revised with traction and body force specifications. See the
benchmark module for examples. Changes include:
(1) var_plot_file now opens in the same directory as the .in file
(2) body force and traction specifications (in that order) are read
from the .in file following all previous input parameters for the
VMS element.
(3) tractions and body forces are calculated for the coarse scale
during the call to RHSDriver.

Finally, there is a memory error that is triggered when the VMS class
is deleted. This error was probably there before the new code was added.

finished implementation of traction BC's and body forces on the coarse
scale equations.

Density added as input parameter, implement later when everyone's ready to modify
all there decks.

Adding density to the Isotropic material class

Adding extra state variable to use as freed node flag.

Add call to inherited function in Initialize function.

Revised Files for Elastoplastic and Rigidplastic Cohesive Surface Models

Remove RGSplit2D from repository and resolve conflicts in RGSplit3D.

Consolidate 2D and 3D volumetric/deviatoric split formulation. Minor updates to VIB formulation.

Deriving MR_RP2DT from TiedPotentialBaseT.cpp